A 12-year-old Hispanic girl, accompanied by her mother, presents with a 1-year history of a red irritated rash in both axillae (Figure 102-1). She has been seen by multiple physicians and has tried many antifungal creams with no results. Even hydrocortisone did not help. She had stopped wearing deodorant for fear that she was allergic to all deodorants. Although the rash barely fluoresced at all, the physical examination and history were most consistent with erythrasma. The patient was given a prescription for oral erythromycin and the erythrasma cleared to the great delight of the patient and her mother.
Erythrasma in the axilla of a 12-year-old Hispanic girl. (Used with permission from Richard P. Usatine, MD.)
Erythrasma is a chronic superficial bacterial skin infection that usually occurs in a skin fold.
The incidence of erythrasma is approximately 4 percent.1
Both sexes are equally affected.
The inguinal location is more common in males.
Etiology and Pathophysiology
Corynebacterium minutissimum, a lipophilic Gram-positive non–spore-forming rod-shaped organism, is the causative agent.
Under favorable conditions, such as heat and humidity, this organism invades and proliferates the upper 1/3 of the stratum corneum.
The organism produces porphyrins that result in the coral red fluorescence seen under a Wood lamp (Figure 102-2).
Coral red fluorescence seen with a Wood lamp held in the axilla of a patient with erythrasma. (Used with permission from the University of Texas Health Sciences Center, Division of Dermatology.)
Erythrasma is a sharply delineated, dry, red-brown patch with slightly scaling patches. Some lesions appear redder, whereas others have a browner color (Figures 102-3 and 102-4).
The lesions are typically asymptomatic; however, patients sometimes complain of itching and burning when lesions occur in the groin (Figure 102-3).
Light brown erythrasma in the groin of a young man. It does not have the degree of scaling usually seen with tinea cruris. (Used with permission from Dan Stulberg, MD.)
Brown erythrasma in the groin of a young man with diabetes. (Used with permission from the University of Texas Health Sciences Center, Division of Dermatology.)